Paper machinery



May 2, 1944. s A. STAEGE PAPER MACHINERY 2 Sheets-Sheet 1 Filed May 25,1940 Bnventor y 1944- s. A. STAEGE 2,347,850

PAPER MACHI'NERY Filed May 25, 1940 2 Sheets-Sheet 2 Q Zmvcmor GttomegPatented May 2, 1944 PAPER MACHINERY l a Stephen A. Staege, Hamilton,Ohio, asslgnor to The Black-Clawson Company, Hamilton, Ohio, acorporation of Ohio I Application May 25, 1940, Serial No. 337,230

2 Claims.

This invention relates to the art of paper making.

One object of the invention resides in the process, in the manufactureof paper, in which paper pulp, after the pulping operation has beencompleted, is screened and supplied at the required pressure andrequired rate of flow directly from the screen to a making wire.

Another object resides in the process of making paper. in which paperpulp is screened and then immediately mixed with white water returnedfrom the forming wire, the mixing action taking place in the screeningapparatus to obtain a consistency suitable for application to theforming wire without further change.

Another object resides in the process of making paper in which the paperpulp together with white water returned from the cylinder mold of apaper making machine is supplied to a screen and the screening actiontakes place at a consistency above that required at the cylinder mold,some of the white water passing through the cylinder mold being returnedtogether with the vat overflow stock and mixing with the screened stockto reduce the consistency to the value required at the cylinder mold. I

Another object is the provision of apparatus adapted to carry out theprocess referred to.

Further objects and advantages of the invention will be apparent fromthe following description, the appended claims and the accompanyingdrawings, in which Fig. 1 is a side elevation of paper making apparatusembodying and for practicing the present invention, a portion of thescreen being shown in central vertical section;

Fig. 2 is a horizontal section on the line 2-2 of Fig. 1;

Fig. 3 is an end view of the cylinder. mold vat, a portion being shownin central vertical section;

Fig. 4 is a top plan view of the vat;

Fig. 5 is a side elevation of a portion of a paper making apparatus ofthe Fourdrinier type, embodying and for practicing the invention, aportion of the fiow passage being shown in section; and

Fig. 6 is a top plan view corresponding to Fig. 5 but showing a portionof the flow passage in horizontal section.

Referring more particularly to the drawings by reference numerals, likeparts being designated with the same reference numerals in the severalviews, Figs. 1 to 4, inclusive, show the preferred embodiment of theinvention as embodied in a paper making apparatus of the cylinder moldtype in which paper pulp is supplied to the'cylinder mold vat at a ratein excess of that required for paper formation so that an excessoverflow of pulp is provided. The cylinder mold, which is shown at [0,operates in the vat ll, the direction of turn of the'cylinder mold beingclockwise as shown in Fig. 3, and the pulp being supplied to the pulppassage l2 adjacent the downturning side of the forming wire, excesspulp overflowing the dam l3 into an excess pulp chamber M. The excesspulp fiow is conducted from the chamber l4 by a pipe l5. As the form'-ing wire rotates in the vat, the fibers are deposited on it, and waterpasses through the wire and flows out through lateral openings 16 intothe white water chambers I! and I8. A'longitudinally extending conduit20 connects the two white water chambers l1 and I8 to the white waterwithdrawal pipe 2|. I

Paper pulp is supplied to the vat through pipe 23 which connectsdirectly to one end of the distributing conduit 24, the opposite end 25of this conduit being connected to a supply pipe 26 which extends acrossthe vat below the distributing conduit and connects to the pipe 23 sothat a flow of pulp takes place into the conduit 24 from opposite endsof the vat. A manually controllable valve 21 may be operated toadjustably restrict flow from pipe 23 into the adjacent end of theconduit 24 in order that the axial rate of flow toward the center of thevat from the opposite ends of the conduit 24 may be equalized.

The conduit 24 is provided with a diagonal-- ly extending baille wall 29the upper end of which is located adjacent a diagonally extendingorifice 30 provided between the ends of the upper wall portions 3| and32 of conduit 24 so that pulp entering the two tapered passages 33 and34 from opposite ends of those passages will be mixed together at thetop of the wall 29 and flow through the elongated orifice3fl'with avelocity that is equalized throughout the length'of the conduit 24. Thisfiow of pulp is deflected by a horizontally extending wall 36 so thatany stock bundles or groups will be effectively bro ken up as thestreams issuing from the two passages 33 and 34 engage one another andthen strike the wall 36. The pulp entering the cov ered compartment 31above the wall portions 3| and 32 is preferably vibrated or agitated, asby flowing through a perforated slowly rotating hollow cylinder 38 tomaintain the fibers in a dispersed condition in the water and break upany fiber groups, and enters the passage l2 of the vet,

preferably in a downward direction. An adjustable wall 39 capable ofbeing adjusted as to height afiords a control of the direction of pulpflow adjacent the downturning side of the forming wire and prevents thepulp from .being drive into the meshes of the. wire.

The opposite ends of the wall 29 are spaced a small distance from theside walls of the conduit 24 to insure some small flow past these endsand around baille 35 to the larger ends of the adjacent passages, thusavoiding the retention of any bodies of slowly moving pulp at the narrowends of these passages.

The supply of pulp to the system comes in through a controllable valve49 and the pulp supply pipe 4| which leads to the white water pipe 2|.The pipe 2| conducts the white water coming from the white watercompartments l1 and .I8 to a pump 42 which returns the white watertogether with the pulp added through pipe 4| through a pipe 43 to thesupply end of a screening machine 44. This screening machine includes asubstantially cylindrical casing wall 45 enclosed at its top by theplate 46 which has a passage through which the pulp to be screened issupplied fromthe pipe 43. Within the wall 45 is a stationary cylindricalscreen 41 through which the pulp must travel in passing. from the supplychamber 48 of the screen to the annular discharge chamber 49 which isbetween the screen and the wall 45. Thescreened pulp is discharged fromthe chamber 49 at one-side of the screen through the outlet 59 into thepipe 23.

Passage of the pulp through the screen 41 is greatly facilitated by alarge number of scraping blades having a construction as more fullydisclosed in my prior application Serial No. 285,- 362 filed July 19,1939. These blades extend along the inner surface of the screen and arecarried yieldingly by springs 53 mounted on carrying rings 54 of arotatable spider which is connected to a motor driven shaft and turnedat a comparatively slow rate of speedof the order of about one turn persecond so that the creation of any large centrifugal force on the fluidin the screen is avoided. The blades provide an effective scrapingaction on the inner surface of the screen, and in view of thecomparatively slow rate of speed and the comparatively large number ofblades, each screen opening will be cleaned many times persecond withoutcausing the mass of pulp within the screen to rotate to such extent asto provide substantial centrifugal force. The rate of flow through thescreen is dependent upon the pressure of the stock supply to the inletchamber 48, as the blades keep the screen openings from clogging, andthe pump 42 is of such character as to give a flow rate and produce therequired pressure on the pulp'to provide the required rate of flow tothe vat. The rate of flow through the pump 42 is controlled, preferablyby a suitable control valve 56 in the white water pipe 43.

Any lighter impurities, foam, etc., that may tend to collect at the topof the screen, at its inlet side, flow up through the upwardly extendingpipe 52 which extends high enough so that these impurities may beretained and periodically discharged. The heavy impurities that settledown, due to gravity effect, in the lower porpulp with the returningwhite water and overflow pulp there is no need for the usual mix box.The screen is adapted to handle very large quantities of pulp and supplythe pulp under pressure so as to give a direct flow from the screen tothe. cylinder mold through a closed passage of comparatively shortlength. Inasmuch as the circuit from the vat back to and through thescreen andto the vat again is closed there is little chance for foam todevelop.

The overflow pulp from the vat, which enters the compartment I4, iscarried back to the screening machine, together with such quantities ofthe white water as is not required to be mixed with the new pulp comingin through the pipe 4|. the pipe |5, travels to return pump 51, the pipeI5 communicating with the white water source as by means of a pipeconnection 58. The white water, in excess of that required to reduce thenew pulp entering the system to the consistency desired for screening,is forced by pump 51 through a pipe 59 which leads to an outwardlyflaring passagefifl preferably formed as apart of the wall 45 of thescreening machine. Some of the white water and the excess overflow pulpfrom the vat is thus returned to the discharge side of the screen, sothat the previously screened pulp of the vat overflow will not berescreened, although, if desired, some or all of the white Water isreturned through pump 57 while the returning excess overflow stock maybe returned through the pipe 2| to the inside of the screen and passagain through the screen so as to be thoroughly deflocculated beforepassing to the vat again. The returned excess pulp and the white wateris very intimately mixed with the screened pulp emerging from the screenopenings as the returned white water passes around on opposite sides ofthe screen in its flow to the discharge passage 50.

The consistency of the pulp required at the vat may be of the order of afew tenths of one per cent, or even considerably less than onetenth ofone per cent. The consistency of the new pulp added to the systemthrough the pipe 4| may be of the order of three or four per cent ormore. It is quite desirable to screen the pulp, in a screen of thecharacter described, at a consistenecy higher than thatrequired by thevat and much less than the consistency of the new pulp supply. Thedescribed arrangement gives great flexibility to the screening action asthe tion of the inlet chamber 48 may be periodically withdrawn through apipe 55 which extends down from the bottom of the screening chamber. TheI pump 42 and mixed by the pump itself with the incoming higherconsistency pulp entering through pipe 4| may be controlled to provide ascreening operation that takes place at a desired consistency, say ofthe order of one-half per cent, or at a higher consistency of one or twoper cent if required to provide a higher screening capacity. Theconsistency of the pulp being screened should be such as to provide aneffective screening and cleaning action, lower consistencies permittingthe heavy particles or impurities to settle more readily provided therate of flow out to the screening surfac is not-so rapid as to carry theheavy particles along with it. The other white water entering thecylinder mold and not returned through the pump 42', is returned throughthe pipe l5 and mixed with the vat overflow pulp and this mixture issupplied to the discharge side of the screen and intimately mixd withthe screened pulp at the screening zone. This reduces the consistency ofthe pulp supplied This overflow stock, which passes through I throughthe screen openings to thelow value de-' screen will be maintained untilthe pulp reaches the forming wire, there being insufllcient time orlength of travel for the stock fibers to collect or group together. Ifthere should be any lack of uniformity in the pulp consistency in theshort length of'travel of the fibers to the tapered passages 33 and 34of the distributing conduit, the merging action of the streams fromthese passages as the stock flows through the orifice 38, and thefurther agitating action produced as the stock flows through the holesof the perforated cylinder 38 will provide a very uniform distributionand defiocculation of the fibers at the point where they enter the vat.

Figs. and 6 of the drawings show a modifica- I tion of the invention asapplied to a Fourdrinier type of paper making machine. The forming wire62, in this construction, travels over the breast roll 63', stock beingsupplied through the slice or orifice 64 the width of which may beadjusted by an adjusting device designated 65. The white waterwhichfiows through the wire as the fibers are deposited, isconducted'down to a receiver 66 and is withdrawn through pipes 67 and68, the former being provided with an adjustable valve 69 which governsthe rate of flow through pipe 61. Pulp is supplied to the system througha pipe 18 having a control valve H and is mixed with the White waterflowing through pipe 61 and pumped by the pump 12 to the inlet side ofthe screening machines 13 and 14 which are similar in construction tothe screening machine of Figs. 1 to 4. A suitable number of thesescreens are provided to take The remaining quantities of white waterpassing to the receiver 86 from the wire is returned to the systemthrough pipe 68, pump 11, pipe 18 and branch-pipes l9 and 80 which leadto the sides of the screening machines and conduct this white water tothe discharge side of the screens to flow around the outside of thescreens and mix with the screened pulp emerging from the screenopenings, reducing the consistency of the pulp in the discharge chamberof the screens to'some suitable consistency less than that obtaining atthe supply side of the screens, and suitable for supply to theFourdrinier wire. The pulp, at suitable low consistency, is conductedthrough pipes 8| and 82 to opposite sides of the distributing conduit84, which is provided with a diagonally extending baflie 85 extendingfrom a point closely adjacent one corner of the'conduit to a pointclosely adjacent a diagonally opposite corner. The top of this wall 85is slightly below a mixing orifice 88 so that the pulp discharges fromthe. two tapered passages 81 and 88, passes through the diagonallyextending orifice 86, and emerges with a uniform velocity throughout thetotal length of the conduit 84. The stock then passes through the holesof a perforated rotatable cylinder 89 towards which it is deflected bythe battle wall 98 arranged above the orifice 86, and then flows to theslice or orifice 64. As will be apparent, the flow path from the screento the slice is quite short and the fibers will be maintained in thethoroughly distributed and dispersed condition in which they leave thescreen until they reach the forming wire, although if there should beany tendency for the fibers to group together they will be effectivelybroken up as they pass through the mixingorifice 86 and through theholes in the rotatable perforated cylinder 89. The pulp will be suppliedthrough the slice 64 at the required pressure necessary to give thedesired rate of flow of the stock at that point, this pressure beingproduced by the pumps 12 and 71 which return the white water under arequired pressure head.-

While the forms of apparatus and the processes herein describedconstitute preferred embodiments of the invention, it is to beunderstood that the invention is not limited to these precise forms ofapparatus and processes, and that changes may be made therein withoutdeparting from the scope of the invention which is defined in theappended claims.

What is claimed is:

1. In a paper making apparatus, an enclosing screen casing, an annularscreen within said casing and spaced from the walls of the casing,

means for supplying pulp to the inside of the' ing wire, av receiver forwater flowing through the wire, means for returning water from saidreceiver to the inside of the screen, and means for supplying some ofthe water from the receiver to the supply opening of the casing to flowaround the screen and mix with the screened pulp.

2. In a paper making apparatus, a forming wire, a closed screen casinghaving a pulp screen and having inlet and discharge chambers, a pressuretight passage leading from the discharge chamber of the screen casing tothe forming wire, a receiver for water flowing through the wire, a waterreturn pipe connected to said receiver, a water pump connected to saidpipe and to the inlet'chamber of the screen casing for returning waterto the screen under pressure to maintain the screen chambers filled withliquid, a pulp supply passageconnected to the water pipe ahead of thewater pump for supplying pulp to the apparatus, and means for supplyingsome of the water from the receiver to the discharge chamber of thescreen casing to mix in the discharge chamber with the screened pulp.

STEPHEN A, STAEGE.

